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Split-bolus dual-energy CT urography: protocol optimization and diagnostic performance for the detection of urinary stones


Karlo, Christoph A; Gnannt, Ralph; Winklehner, Anna; Fischer, Michael A; Donati, Olivio F; Eberli, Daniel; Sulser, Tullio; Alkadhi, Hatem; Stolzmann, Paul (2013). Split-bolus dual-energy CT urography: protocol optimization and diagnostic performance for the detection of urinary stones. Abdominal imaging, 38(5):1136-1143.

Abstract

PURPOSE: Prospective protocol optimization, determination of image quality and diagnostic performance of virtual non-enhanced images (VNEI) derived from split-bolus dual-energy computed tomography (DECT) urography in patients with urinary stones. METHODS: IRB-approved, prospective study of 100 patients who, after written informed consent, underwent single-energy, non-enhanced CT and split-bolus, contrast-enhanced DECT (30 + 50 mL of contrast media; combined nephro-urographic acquisition). DECT was performed using setting A (80/140 kVp) in the first 20, and setting B (100/140 kVp) in the second 20 patients. Tin filtration was used in all patients. After a pre-analysis of VNEI quality, 60 additional patients were examined using setting B. Two readers qualitatively and quantitatively determined image quality of all weighted-average DECT images regarding urinary tract opacification (n = 100), and all VNEI regarding quality of iodine subtraction and urinary stone detection (n = 80). True nonenhanced (TNEI) images were the standard of reference for statistical analysis (inter-reader variability and diagnostic performance characteristics). RESULTS: The urinary tract was completely opacified in 94% (94/100) of patients. Iodine subtraction was improved (p < 0.01) and image noise of VNEI was lower (p < 0.05) in DECT setting B. On VNEI, 83% (86/104) of urinary stones were correctly identified and 17% (18/104) were missed. Stones missed (2.5 mm, 1-4) were significantly smaller than stones correctly identified (5 mm, 2-27; p < 0.001). Diagnostic accuracy was 98% on a per-renal-unit basis and 96% on a per-patient basis. Inter-reader agreements were excellent (κ = 0.91-1.00; ICC = 0.86-0.99). CONCLUSIONS: Split-bolus DECT urography was technically feasible and quality of VNEI was improved with the 100/140 kVp setting. Detection of urinary stones <4 mm on VNEI was limited.

Abstract

PURPOSE: Prospective protocol optimization, determination of image quality and diagnostic performance of virtual non-enhanced images (VNEI) derived from split-bolus dual-energy computed tomography (DECT) urography in patients with urinary stones. METHODS: IRB-approved, prospective study of 100 patients who, after written informed consent, underwent single-energy, non-enhanced CT and split-bolus, contrast-enhanced DECT (30 + 50 mL of contrast media; combined nephro-urographic acquisition). DECT was performed using setting A (80/140 kVp) in the first 20, and setting B (100/140 kVp) in the second 20 patients. Tin filtration was used in all patients. After a pre-analysis of VNEI quality, 60 additional patients were examined using setting B. Two readers qualitatively and quantitatively determined image quality of all weighted-average DECT images regarding urinary tract opacification (n = 100), and all VNEI regarding quality of iodine subtraction and urinary stone detection (n = 80). True nonenhanced (TNEI) images were the standard of reference for statistical analysis (inter-reader variability and diagnostic performance characteristics). RESULTS: The urinary tract was completely opacified in 94% (94/100) of patients. Iodine subtraction was improved (p < 0.01) and image noise of VNEI was lower (p < 0.05) in DECT setting B. On VNEI, 83% (86/104) of urinary stones were correctly identified and 17% (18/104) were missed. Stones missed (2.5 mm, 1-4) were significantly smaller than stones correctly identified (5 mm, 2-27; p < 0.001). Diagnostic accuracy was 98% on a per-renal-unit basis and 96% on a per-patient basis. Inter-reader agreements were excellent (κ = 0.91-1.00; ICC = 0.86-0.99). CONCLUSIONS: Split-bolus DECT urography was technically feasible and quality of VNEI was improved with the 100/140 kVp setting. Detection of urinary stones <4 mm on VNEI was limited.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Diagnostic and Interventional Radiology
04 Faculty of Medicine > University Hospital Zurich > Urological Clinic
Dewey Decimal Classification:610 Medicine & health
Date:2013
Deposited On:19 Mar 2013 13:40
Last Modified:05 Apr 2016 16:42
Publisher:Springer
ISSN:0942-8925
Publisher DOI:https://doi.org/10.1007/s00261-013-9992-9
PubMed ID:23503617

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